Hiya, i have a Audi A4 turbo diesel 2.5 V6 engine, its 1999 (T) but i think it has a problem with its turbo, and was wondering whether anyone would know?
It basically feels like the turbo is never kicking in, and when i'm travelling on the motorway it grudgingly accelerates to about 80mph, but my foot is nearly flat on the floor? ... i have also noticed it takes a while to start the car in the mornings, its always o.k when the engine is hot (starting that is)
what can it be? someone suggested to me the air mass meter?
Thanks natalie
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This could just be a simple MAF failure, as the symptoms match perfectly. The turbos are usually quite reliable and dont usually fail suddenly. Also, a failed turbo may give a lot of blue smoke from the exhaust when revving the engine with the car stationary.
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Thanks for your advice, but i'm not sure what a MAF failure is? sorry you might have to elaberate?..... I don't think ive noticed any blue smoke from the exhaust when revving engine with car stationary, but i could give it a go now!! Thanks natalie
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me again! ... just gone and tried it, now you come to mention it, when i just started it up then a load of smoke came out, and it looked vaguely blue in colour (off whitish) it also revs up very grudingly when stationary?
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Before you go any further with possible component replacement,I would suggest that engine crankcase breather system filter is replaced.This part is often overlooked and can cause all types of performance/ smoking related problems.
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And after that, have a dealer check the MAF -- Mass Air Flow meter. It's just downstream of the engine air filter and measures the amount of air coming into the engine so that the engine management can inject the right amount of fuel.
If it fails the engine management cannot calculate how much fuel is needed = zero power, smoke etc etc
They are a known weakspot, cost about £70 if memory serves.
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The 2.5 uses a Hitachi MAF which don't fail like the BOSCH ones used on the 1.9 etc...
If you do need one for the V6, I may have a boxed brand new one you can have really cheap.
I have had problems with two vacuum control valves, one controlled the EGR valve, and the other the turbocharger vanes N75 and N??. These caused similar symptoms. I will post more info later, and take some pics, to see if yours look the same.
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The first money you should spend on this car is for the fault codes to be read and cleared.
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Hiya, thanks for all your advice, i did exactly what the Dox suggested and got a diagnostic test done, the fault codes were as follows:
1) 00523 - intake air temperature sensor (G42)
2) 00550 - injection start control
3) 00542 - stroke sensor nozzle needle (G80)
4) 01318 - ECU for injection pump (J399)
5) 00553 - mass air flow sensor (G70)
so i'm guessing number 5) means that the air mass meter needs replacing? but does anyone know what the other codes mean? cheers natalie
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2 and 3 are related to the sensor in one of the injectors. (the one that has an electrical connector as well as metal pipes)
2 is the issue
3 is the alleged faulty part
I'm surprised there are so many faults.
5) Suggests the MAF, but be aware that these are not part replacement instructions, and as an example, I had MAF errors, (hence me having a spare) but the fault was an EGR valve being kept open, and the ECU not seeing a corresponding dip in the MAF reading when a signal was sent to open the EGR (because it was already open)
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Have the codes been cleared? How does the car now drive?
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Thanks for replying both of you.
I asked the guy to clear the fault codes, but he said there was not an option to clear them like usual?
Ive just done abit of research on internet, I think number 1 & 5 are linked, number one is part of 5, so either i need a new air mass meter or its like you said about the valve problems? (would you mind telling me abit more about the valve problems and how to tell if it is that? that would be helpful? if it turns out to be the air mass meter then sure i would be happy to purchase yours?)
as you said as well, codes 2 & 3 are linked, it sounds like i need a new G80 sensor (or needle motion sensor) which is located in one of the injectors, might need to replace the whole injector, anyone know of any places that sell that sort of thing fairly cheap?
so its just fault number 4, 01318 - ecu for injection pump (J399) which is foxing me?
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The thing to do now is to get the codes cleared and drive the car again, if they're genuine codes they'll reappear. Some of those could be ghost codes due to un plugging componenets when the ignition is turned on.
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When the codes are read on VAGCOM, it usually states whether they are intermittent or present etc..
It's not unusual to have a few built-up over time, if they haven't been cleared.
I agree the best thing to do is clear the codes, and see if/when they come back, some may not.
I'll post the part number of the MAF and if yours matches, let me know.
When mine was replaced, I also needed an adaptation doing by the garage, I think it is some sort of calibration with the new part fitted.
You could always try driving with it disconnected, and see if driveability improves, but I wouldn't leave it unplugged even if it improves things, as it can cause high speed stumbles that shock load the transmission.
On most Bosch Motronic systems, If a needle-lift sensor fault is present , it usually causes a limp-mode where fuel mass per stroke (mg/S) is limited to a smaller amount.
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